Recently Used List

Develop a recently-used-list class to hold strings uniquely in Last-In-First-Out order.

• The most recently added item is first, the least recently added item is last.
• Items can be looked up by index, which counts from zero.
• Items in the list are unique, so duplicate insertions are moved rather than added.
• A recently-used-list is initially empty.

(Source: https://github.com/garora/TDD-Katas)

Interface

public class RecentlyUsedList {
    public init()
    public var size: Int { get }
    public subscript(index: Int) -> String { get }
    public func insert(_ element: String)
}